1. Field of the Invention
The invention relates to a connector for doubly locking terminal fittings.
2. Description of the Related Art
Japanese Unexamined Utility Model Publication No. 4-102576 discloses a connector that performs a function of doubly locking terminal fittings. This connector has a housing formed with cavities for receiving terminal fittings. Each terminal fitting is inserted into the cavity from behind and engages a resiliently deformable lock in the cavity. Forces exerted by the terminal fitting deform the lock. However, the lock resiliently returns to engage and lock the terminal fitting when the terminal fitting reaches a proper insertion position. A front retainer is assembled to the front of the housing in this state, and fasteners of the front retainer fit into deformation spaces for the locks to prevent the locks from deforming out of engagement with the terminal fittings. In this way, the locks directly fasten the terminal fittings and the front retainer indirectly fastens the terminal fittings by preventing the deformation of the locks.
A degree of deformation of the lock toward the deformation space in the above-described connector corresponds to an area of engagement of the lock with the terminal fitting. Accordingly, a larger degree of deformation of the locks may be provided to increase the area of engagement of the terminal fittings and the locks.
However, an increase in the degree of deformation of the lock in the inserting process of the terminal fitting results in an increase in the resilient restoring force that accumulates in the lock is increased. Friction between the lock and the terminal fitting increases accordingly. This leads to an increase in resistance against the insertion of the terminal fitting, and also to buckling of a wire if the inserting operation is performed by gripping the wire. As a result, smooth inserting operation of the terminal fitting is hindered.
The present invention was developed in view of the above problem and an object thereof is to improve the reliability of a terminal fitting locking function without reducing the insertion operability of a terminal fitting.
The invention relates to a connector with a housing formed with at least one cavity into which at least one terminal fitting is insertable. A lock is formed in each cavity and interferes with the terminal fitting in the process of inserting the terminal fitting into the cavity. The lock deforms during insertion of the terminal fitting into the cavity. However, the lock is restored resiliently to engage and lock the terminal fitting when the terminal fitting reaches or is close to a proper insertion position. The connector also includes a retainer to be assembled with the housing. The retainer presses and deforms the lock toward the corresponding terminal fitting when the retainer is fit into the deformation spaces. The area of engagement of the lock and the terminal fitting is increased by as much as the deformation of the lock caused by the retainer. Accordingly, the degree of the deformation of the lock during insertion of the terminal fittings is low and the resistance that acts when the terminal fitting is inserted is suppressed.
The lock preferably returns toward its free state and engages the terminal fitting to lock the terminal fitting when the terminal fitting reaches a proper insertion position. The lock preferably is pressed by the retainer and is deformed toward the corresponding terminal fittings from the free state when the retainer is fitted into the deformation space.
The retainer preferably enters the deformation space for the lock to prevent the lock from being deformed in a direction to be disengaged from the terminal fitting when the retainer is assembled with the housing.
The housing preferably has a plurality of cavities, and a wall forming a front end of each cavity preferably projects independently of the other cavities. The retainer may have engageable portions that engage and surround the walls forming the front ends of the cavities. Fittable portions are formed on the engageable portions of the retainer and fit into the deformation spaces.
The engageable portions of the retainer surround the walls forming the front ends of the cavities and make no loose movement with respect to the cavities or the terminal fittings inserted into the cavities. Thus, the fittable portions on the engageable portions can securely resiliently deform the locks toward the corresponding terminal fittings without loosely moving with respect to the cavities and/or the terminal fittings.
The fittable portions preferably are thrust into a space between the locks and a corresponding portion of the housing to deform the locks. Accordingly, the locks can be more deformed more reliably and with a greater force.
Each lock preferably is cantilevered forward and an extending end of each lock serves as a locking section engageable with the terminal fitting to lock the terminal fitting.
A lock could be formed with a catch for a disengagement jig, and the catch could extend from a locking section that engages with a terminal fitting. This catch could interfere with the outer surface of the terminal fitting to restrict a degree of resilient deformation of the lock when the lock is deformed from its free state. Contrary to this, the present preferred embodiment has locks that are cantilevered and the extending ends engage the terminal fittings. Thus, the locks have no part comparable to the catch that can interfere with the outer surfaces of the terminal fittings. Therefore, a large degree of deformation of the locks to engage the terminal fittings can be ensured.
Each lock preferably is cantilevered substantially forward and the retainer contacts the locks behind positions of engagement between the locks and the terminal fittings. Additionally, the housing and/or each terminal fitting preferably comprise a displacement preventing portion for preventing a locking section of the lock engageable with the terminal fitting from being displaced toward the corresponding terminal fitting.
A backward pulling force on a terminal fitting creates forces that could cause a lock to buckle so that a portion of the lock between its supporting point of resilient deformation and the position of engagement with the terminal fitting could bend toward the deformation space. However, the retainer of the subject invention contacts the lock from the side of the deformation space between the supporting position of resilient deformation and the position of engagement with the terminal fitting. Thus, the lock undergoes no buckling deformation and cannot bend toward the deformation space. Further, the extending end of the lock is prevented from a displacement in a direction away from the retainer and toward the terminal fitting. Therefore, the retainer is held in contact with the lock and a function of the retainer for preventing a buckling deformation cannot be degraded.
According to a further preferred embodiment, a movable surface substantially facing a side opposite from the deformation space is formed at a side of each lock. A sidewall forming the cavity and arranged along the side of the lock is formed with a receiving surface substantially facing the movable surface, and the movable surface is proximate to or substantially in contact with the receiving surface while the retainer resiliently deforms the locks toward the corresponding terminal fittings.
The cavities are exposed to outside via the clearances between the sidewalls and the sides of the locks. Thus, a leak or opening may occur between the terminal fittings inserted in the adjacent cavities. However, the movable surfaces of the locks come to be proximate to or in contact with the receiving surfaces of the sidewalls in the present invention. Thus, the clearances between the sidewalls and the locks are closed to prevent a leak.
The movable surface preferably is substantially parallel with or converging toward the receiving surfaces in the free unbiased state of the lock where it is not deformed.
The lock and/or the retainer preferably comprise at least one slanted guiding surface for guiding the lock into engagement with the terminal fitting.
The lock preferably has an inverted T-shaped cross section that is transversely symmetrical.
These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments.